Astronomers Discover New Nearby Galaxy - 2003-11-06

An international team of researchers has discovered a nearby galaxy, whose stars are being absorbed by our own galaxy, the Milky Way.

The newly discovered galaxy is called Canis Major, a dwarf galaxy of more than a billion stars about 25,000 light years away. Canis Major is is the closest of a dozen small galaxies orbiting the Milky Way. Astronomers say it is about one-percent the size of our galaxy.

Because Canis Major is so small, British astronomer Michael Irwin says the gravitational force of the Milky Way is ripping it apart and incorporating its stars into our own galaxy. "The sort of milky plane is being added to by this new galaxy," he said.

Professor Irwin, an astronomer at the University of Cambridge in England, is part of the team that discovered Canis Major.

The astronomers found the dwarf galaxy by using an infrared telescope. The infrared device allows astronomers to peer beyond the clouds of dust inside the Milky Way, and see stars that shine brightly.

"And what we found was an obvious excess of objects just to the south of the galactic plane," he said. "And we now think this is the remnant of this galaxy that is being dissolved away as it goes around the Milky Way."

Canis Major is the second small galaxy to be discovered in recent years that is contributing to the Milky Way's girth. The other constellation, the Sagittarius dwarf, is also colliding with the Milky Way.

Steve Maran of the American Astronomical Society says the discovery of Canis Major gives astronomers a first-hand look at the growth of the Milky Way. He says it provides evidence that our galaxy is reaching maturity.

"I do not think there is anything left for the Milky Way to swallow that is going to make a big difference in the forseeable future. But it is still cleaning up the odds and ends," he said.

A description of the discovery of Canis Major will be published in a journal of the Royal Astronomical Society.